Hi-Pot Testing Control Panels

[DaveRosser]

I have some questions regarding hi-pot testing of equipment.
We manufacture automation equipment and are looking in to hi-pot testing the control panels and control system. My question is what needs to be tested...
The control panels consist of contactors, relays, disconnects, inverters, plc's etc... most of which have been hi-pot tested by the manufacturer. So do i just test all of the remote wiring? and how do i do that without damaging equipment...

any help is greatly appreciated

 

[sdmays]

Is this for some agency listing? If so, then you would just have to become familiar enough with the applicable standard, etc...

The most common hi-potting scenario with which I am familiar is hi-potting between all the wires tied together and the control panels. If all the wires are tied together, there is no reasonable way to destroy a given piece of equipment. Any resulting breakdown will either a result of nicked wire insulation, poor design of a given piece of equipment (which should have been handled by the manufacturer of the equipment), or careless construction of your automation equipment...

 

[VEBill]

...but you don't normally hi-pot test a panel with the active electronics (inverters, PLCs) installed. Usually, it is just the plain old panel itself being tested (wires, connectors, maybe switches) - nothing low voltage.

 

[DaveRosser]

So for practical purposes, I would test all the wires before they are terminated? What we do is build and wire the backplate's for the panels on a bench, and then install them into the cabinets when complete. We then do the remote wiring and terminations. But by what you are saying, we dont need to test the low voltage(120vac/24vac) control wiring, just the high voltage (480/600vac)?

As far as agency listing, we would like to build the machiney with CE compliance. As well, the hi-pot testing has been recommended as a good manufacturing procedure by an outside agency. To be honest, we've never had any problems without the testing, but i guess it is a good idea to do..

 

[sdmays]

Yes, that is true...back to the question regarding agency listing.

During my days working for a custom automated test equipment outfit we never had any kind of agency listing and we never hipotted anything. Amongst many other things, our equipment was responsible for controlling a hi-pot tester and was also responsible for connecting the output of the hi-pot tester to the DUT, but we never hi-potted our equipment (I suppose you could say part of our equipment was hi-potted every time a product went down the assembly line...).

 

[RobertLoop]

Your panel should be tested in its most fully configured, final stage of assembly. Typically, this is the point where your product is next going to boxed/shipped/warehoused.

The purpose of the hi-pot test is to find a weak link in the insulation caused by inadequate materials or poor/damaged construction.

It's also important to ramp up/ramp down your test potential voltage slowly so that you do not inadvertantly punch a hole in the insulation (your test standard should give some guidelines on volts/sec).

Your test should encompass all wiring/components where primary mains AC is typically present during normal operation, which would include 120 VAC and above.